Science —

Nitrous oxide reduction method makes useful chemicals

Environmental chemists combine nitrous oxide removal with the production of …

Nitrous oxide is both a greenhouse gas and contributes to the destruction of stratospheric ozone. Industry produces around 1.3 megatons of nitrous oxide per year, which accounts for a fifth of the total anthropogenic emissions. Thus, there is great interest in finding methods to reduce nitrous oxide emissions. The most economically attractive proposals involve combining nitrous oxide removal with the production of useful chemical products.

One of the methods employs Fe-MFI zeolites as catalysts to use nitrous oxide to convert benzene to phenol, or propane to propene. Although Fe-MFI zeolites show great promise, there are severe disadvantages. The presence of oxygen and other nitrogen oxides deactivates the catalytic ability and selectivity of Fe-MFI zeolites. Since industrial emissions that contain nitrous oxide are often contaminated with oxygen and a variety of other nitrogen oxides, it is essential to develop a catalyst that can operate in this chemical mixture.

In Angewandte Chemie, environmental chemists describe the utility of Na/CaO—calcium oxide doped with sodium oxide—as a catalyst for the simultaneous abatement of nitrous oxide and production of hydrogen gas and ethylene. They took advantage of the large amount of heat given off during nitrous oxide decomposition to thermally dehydrogenate ethane, producing ethylene and hydrogen gas. Both products have industrial uses. The Na/CaO catalyst is able to remove nearly 100 percent of nitrous oxide at various concentrations in gas mixtures (from 0.15 to 40 volume percent). The conversion of ethane to ethylene and hydrogen gas occurs with an efficiency of greater than 50 percent. The presence of water, oxygen, various nitrogen oxides, and carbon oxides do not diminish the catalytic performance of Na/CaO.

Although Na/CaO is almost 100 percent effective at removing nitrous oxide, the conversion of ethane to ethylene and hydrogen gas is much less efficient, but it's possible that the conversion yield can be increased by tuning the reaction conditions. Overall, the use of Na/CaO catalyst is a significant improvement on previous nitrous oxide abatement methods.

Latest Ars Video >

The Greatest Leap, Episode 3: Triumph

In honor of the 50th anniversary of the beginning of the Apollo Program, Ars Technica brings you an in depth look at the Apollo missions through the eyes of the participants.

The Greatest Leap, Episode 3: Triumph

The Greatest Leap, Episode 3: Triumph

In honor of the 50th anniversary of the beginning of the Apollo Program, Ars Technica brings you an in depth look at the Apollo missions through the eyes of the participants.

Yun Xie
Yun Xie / Yun Xie is a contributing science writer at Ars, where she covers the latest advancements in science and technology for Ars. She currently works in scientific communications, policy, and review. Emailreenxie@gmail.com//Twitter@yun_xie